RU2801191C1 - High strength concrete - Google Patents

Abstract

FIELD: building materials.

SUBSTANCE: invention is recommended for the manufacture of structures made of concrete or monolithic construction of industrial, civil and special purposes. High-strength concrete obtained from a mixture including wt.%: Portland cement 18.32-19.42; sand with fineness modulus 2.1 30.16-30.56; crushed granite fraction 3-10 mm 39.89-40.39; complex reactive stabilizer with D=0.750 g/cm³, pH=8.3, consisting of the following components, wt.%: blast-furnace metallurgical slag with a specific surface, S=470 m²/kg, 81.06-82.00; aluminous cement 15.35-16.2; methylcellulose 1.05-1.10; polycarboxylate polymer 1.60-1.64, 3.30-3.39; an aqueous solution of a complex chemical additive, p=1.047 g/cm³, pH=6.8, consisting of the following components, wt.%: polycarboxylate polymer 37.74-39.00; macromolecular compound 5.40-5.66; silicon dioxide nanodispersions 22.30-22.64; calcium nitrite 14.80-15.09; calcium nitrate 18.50-18.87; water 7.09-7.16.

EFFECT: increased mobility, reduced delamination of the self-compacting concrete mixture and creation of concrete based on it with increased compressive strength and increased tensile strength in bending.

1 cl, 2 tbl

Description

The invention relates to building materials and can be used for the manufacture of concrete structures, as well as for monolithic construction of industrial, civil and special purposes.

Known mixture for the manufacture of high-strength concrete, consisting of the following components, wt. %: Portland cement 22.48-28.61; sand 23.00-25.60; crushed stone 36.30-39.00; additive 0.69-0.92; water 11.40-12.00, the additive used consists of the following components, wt. %: iron hydroxide sol (III) Fe(OH) ₃ with density ρ=1.021 g/cm ³ and pH value pH=4.0-5.0 99.83-99.87; aluminum sulfate Al ₂ (SO ₄ ) ₃ 0.13-0.17 (RU No. 2332388, S04V 40/00, S04V 22/08, S04V 111/20, S04V 111/27, 08/27/2008).

The disadvantages of this technical solution are: insufficient mobility and insufficient cohesion of the concrete mixture, as well as reduced values of compressive strength and tensile strength in bending.

Known mixture for the manufacture of high-strength concrete containing Portland cement, sand, crushed stone, silica-containing component, represented by a sol of silicic acid H ₂ SiO ₃ with a density of ρ=1.014 g/cm ³ , a pH value of pH=5-6, the additive "DEYa-M" and water in the following ratio, wt. %: Portland cement - 44.4-48.0; sand - 20.0-22.2; crushed stone 20.0-22.2; said silica-containing component - 0.43-0.48; additive "DEYA-M" - 0.43-0.48; water - 10.34-11.04 (RU No. 2256629, С04В 28/04, 07/20/2005).

The disadvantages of this technical solution are: insufficient mobility and insufficient cohesion of the concrete mixture, as well as reduced values of compressive strength and tensile strength in bending.

The closest in technical essence to the claimed invention is a raw mix for high-strength concrete containing Portland cement, sand, crushed stone, a silica-containing component represented by H ₂ SiO ₃ sol with a density of ρ=1.014 g/cm ³ , a pH value of pH=5.0 - 6.0, the addition of potassium ferruginous K ₄ [Fe(CN) ₆ ] and water in the following ratio, wt. %: Portland cement 43.58-47.08; sand 14.43-15.69; crushed stone 25.70-27.84; silica-containing component, represented by a sol of silicic acid H ₂ SiO ₃ with a density of ρ = 1.014 g / cm ³ , a pH value of pH = 5.0-6.0, the addition of potassium iron-cyanide K ₄ [Fe (CN) ₆ ] - 0.44- 0.47; water - 12.10-12.15 (RU No. 2256630, С04В 28/04, С04В 111/20, 07/20/2005).

The disadvantages of this technical solution are: insufficient mobility and insufficient cohesion of the concrete mixture, as well as reduced values of compressive strength and tensile strength in bending.

The problem to which the invention is directed is the creation of a raw mix of increased mobility and increased cohesion for self-compacting high-strength concrete, characterized by increased compressive strength and increased tensile strength in bending.

The task is achieved by the fact that high-strength concrete obtained from a mixture including Portland cement, sand, crushed stone, an additive and water, according to the invention, contains sand with a fineness modulus of 2.1 as sand, contains granite crushed stone of a fraction of 3-10 mm as crushed stone, as an additive contains a complex chemical additive represented by an aqueous solution with a density of ρ=1.047 g/ ^cm3 and a pH value of pH=6.8, consisting of an aqueous solution of a polycarboxylate polymer based on maleic anhydride with a density of ρ=1.027 g/ cm ³ and the pH value of pH=6.2, high-molecular compounds based on the potassium salt of higher fatty acids with a density of ρ=1.056 g/cm ³ , the value of the pH value of pH=9.2; nanodispersions of silicon dioxide used in the form of a Sol of silicon hydroxide with a density of ρ=1.012 g/cm ³ and a pH value of pH=3.1; an aqueous solution of calcium nitrite with a density of ρ=1.038 g/cm ³ , pH value pH=5.7; an aqueous solution of calcium nitrate with a density of ρ=1,040 g/cm ³ , pH value pH=5.8 in the following ratio of additive components, wt. %:

- said polycarboxylate polymer - 37.74-39.00 - specified high molecular weight compound - 5.40-5.66 - said nanodispersions - 22.30-22.64 - said aqueous solution of calcium nitrite - 14.80-15.09 - said aqueous solution of calcium nitrate - 18.50-18.87,

additionally contains a complex reactive stabilizer characterized by bulk density D=0.750 g/cm ³ and pH value pH=8.3, consisting of finely ground blast-furnace metallurgical slag with specific surface area S=470 m ² /kg; aluminous cement; methylcellulose with a bulk density D=0.620 g/cm ³ and a pH value of 7.3 and a poly-carboxylate polymer with copolymers of acrylic acid and methacrylic acid ethyl ester with a bulk density D=0.620 g/cm ³ and a pH value =6.3 with the following ratio of stabilizer components, wt. %:

- specified slag - 81.06-82.0 - aluminous cement - 15.35-16.2 - said cellulose - 1.05-1.1 - said polycarboxylate polymer - 1.6-1.64,

with the following ratio of components of the raw mix of high-strength concrete, wt. %:

-Portland cement - 18.32-19.42 - specified sand - 30.16-30.56 - specified gravel - 39.89 - 40.39 - specified stabilizer - 3.30-3.39 - specified complex chemical additive - 0.14-0.18 - water - 7.09-7.16,

The combined use of a complex chemical additive containing a polycarboxylate polymer based on maleic anhydride in combination with a complex reactive stabilizer containing a polycarboxylate polymer based on polypropylene oxide with copolymers of acrylic acid and methacrylic acid ethyl ester provides a highly fluid mixture for self-compacting high-strength concrete.

The use of a complex reactive stabilizer, which includes methylcellulose and finely ground blast-furnace metallurgical slag with a specific surface area S _sp. =470 m ² /kg, provide increased cohesion of highly mobile concrete mix, reducing the delamination of highly mobile concrete mix.

The use of a complex chemical additive, which includes a polycarboxylate polymer based on maleic anhydride in combination with a high-molecular compound based on the potassium salt of a higher fatty acid, which, in the presence of cement, at an early age, starting from 2 days, enter into chemical interaction forming a branched structure , which has a reinforcing effect on the emerging structure of concrete, which positively affects the increase in tensile strength in bending, starting from an early age, and throughout the entire process of concrete hardening.

The presence of calcium nitrite and calcium nitrate in the composition of the additive enhances the processes of cement hydration at an early age, increasing the compressive strength to the greatest extent.

The increase in compressive and tensile strength in bending at the design age is due to the increased hydration activity of the components of the activated and stabilized concrete mix.

Silicon dioxide nanodispersions, as a result of the formed surface, have increased surface energy at a reduced pH value, which has a positive effect on enhancing hydration processes, forming an increased amount of complex hydrated phases that have a positive effect on the formation of an increased number of contacts in the hardening system, thus, compacting and strengthening the structure of concrete, while increasing the compressive strength of hardening concrete.

In addition, nanosipersions of silicon dioxide, having increased reactivity, enter into synthesis reactions with the resulting hydrate phases, providing the formation of new hydrate phases with a high content of silicon dioxide, SiO ₂ , which, as a rule, differ in increased strength and hardness and crystallize in the form of elongated fibers. , which positively affects the increase in tensile strength in bending.

An increase in compressive strength and, to a greater extent, tensile strength in bending is achieved by hydration of blast-furnace metallurgical slag, since strong and hard, elongated crystals of calcium-magnesium hydrosilicates are formed as hydrated phases under certain conditions. The most effective slag hydration activity is manifested in the presence of aluminous cement, the hydration processes of which are accompanied by the release of a large amount of heat, which is necessary to activate the slag hydration processes.

The claimed set of essential features exhibits a new property when combined with the use of a complex chemical additive consisting of a polycarboxylate polymer based on maleic anhydride, a high molecular weight compound based on a potassium salt of a higher fatty acid, nanodispersions of silicon dioxide, SiO ₂ , calcium nitrite and calcium nitrate and a complex reaction active stabilizer, consisting of aluminous cement, finely ground blast-furnace metallurgical slag, methylcellulose and a polycarboxylate polymer based on polypropylene oxide with copolymers of acrylic acid and methacrylic acid ethyl ester, provides a super-total effect, which consists in creating a highly mobile concrete mixture with increased cohesion, reduced exfoliation, on the basis of which high-strength concrete with increased tensile strength in bending was obtained.

A mixture containing Portland cement, sand with a fineness modulus of 2.1; crushed granite fraction 3-10 mm, a complex chemical additive consisting of an aqueous solution of a polycarboxylate polymer of maleic anhydride, a high-molecular compound based on a potassium salt of a higher fatty acid, silicon dioxide nanodispersions, an aqueous solution of calcium nitrite and an aqueous solution of calcium nitrate, and additionally contains a complex reactive stabilizer, consisting of finely ground blast-furnace metallurgical slag with a specific surface area S _sp. =470 m ² /kg; aluminous cement; methylcellulose and a polycarboxylate polymer with copolymers of acrylic acid and methacrylic acid ethyl ester, provides a highly mobile concrete mixture with increased cohesion, reduced delamination and the production of high-strength concrete on its basis, which has increased compressive and tensile strength in bending.

According to the applicant and the authors, the claimed invention meets the criterion of patentability - inventive step.

The claimed invention is industrially applicable and can be used in civil and industrial construction, as well as at special-purpose facilities.

An example of a specific implementation.

The raw mixture is prepared as follows: 1. Preparation of an aqueous solution of a complex chemical additive with a density of ρ=1.047 g/cm ³ and a pH value of pH=6.8:

1.1. An aqueous solution of a polycarboxylate polymer of maleic anhydride with a density of ρ=1.027 g/cm ³ and a pH value of pH=6.2 is dispensed.

1.2. A high-molecular compound based on a potassium salt of a higher fatty acid with a density of ρ=1.056 g/cm ³ and a pH value of pH=9.2 is dosed.

1.3. The sol of silicon hydroxide with a density of ρ=1.012 g/cm ³ and a pH value of pH=3.1 is dosed, which includes silicon dioxide nanodispersions.

1.4. An aqueous solution of calcium nitrite with a density of ρ=1.038 g/cm ³ and a pH value of pH=5.7 is dosed.

1.5. An aqueous solution of calcium nitrate with a density of ρ=1.040 g/cm ³ and a pH value of pH=5.8 is dosed.

1.6. All components dosed according to p.p. 1.1. - 1.5. transported to a paddle mixer, where the dosed components are mixed for 25 minutes. and after that, the density of the aqueous solution of the additive is controlled and the value of the pH value of the pH, the additive, ready for use, is transported to the storage tank.

2. Preparation of a complex reactive stabilizer characterized by bulk density D=0.750 g/cm ³ and pH value pH=8.3.

2.1. Finely ground blast-furnace metallurgical slag is dosed with specific surface area S _beats .=470 m ² /kg;

2.2. Aluminous cement is dosed;

2.3. Dose methylcellulose with a bulk density D=0,620 g/cm ³ and the value of the pH pH=7.3;

2.4. A polycarboxylate polymer based on polypropylene oxide with copolymers of acrylic acid and methacrylic acid ethyl ester with a bulk density D=0.620 g/cm ³ and a pH value of pH=6.3 is dispensed;

2.5. All components dosed according to p.p. 2.1. - 2.4. transported to a paddle mixer, where the dosed components are mixed for 15 minutes. and after that, the bulk density and the pH of the ready-to-use complex stabilizer are controlled, the ready-to-use complex stabilizer is transported to a storage tank.

3. Preparation of a mixture for high-strength concrete:

3.1. Portland cement PC500 D0 is dosed;

3.2. Dose sand with a fineness modulus of 2.1;

3.3. Dose crushed granite fraction 3-10 mm;

3.4. Dosing water;

3.5. The complex chemical additive prepared according to clause 1.6 is dosed;

3.6. A complex chemical additive, dosed according to clause 3.5, is transported into the dosed water.

3.7. The complex reactive stabilizer prepared according to clause 2.5 is dosed.

3.8. All components dosed according to p.p. 3.1-3.7. transported to a concrete mixer of any modification used in the existing production and thoroughly mixed until a homogeneous, highly mobile mixture is obtained, which is used to manufacture products or carry out monolithic construction from high-strength self-compacting concrete, for which the workability is determined by the spread of the cone in accordance with GOST R 59715-2022 p. 5 “Self-compacting concrete mixes. Test Methods".

The cohesiveness of the concrete mixture is determined by the parameter of the delamination of a self-compacting concrete mixture according to GOST R 59715-2022 p. 8 “Self-compacting concrete mixes. Test Methods".

To determine the compressive strength, cube samples are made with a size of 100 × 100 × 100 mm; to determine the tensile strength in bending, samples are made - prisms with a size of 100 × 100 × 400 mm.

Hardening of all samples is carried out under normal conditions, at an air temperature of 20 ± ° C and a humidity of ≥95%.

Testing of samples for determination of strength indicators is carried out at the age of 28 days in accordance with GOST 10180-2012 “Concrete. Methods for determining the strength of control samples.

The compositions of concrete are presented in table 1, the results obtained are presented in table 2.

According to the test results, it was found that the workability of a self-compacting concrete mixture, determined by the spread of the cone, increases by 2.1 times, the delamination of the concrete mixture decreases by 47%, the compressive strength increases by 38%, and the tensile strength in bending by 71%.

Claims (6)

High-strength concrete obtained from a mixture including Portland cement, sand, crushed stone, an additive and water, characterized in that it contains sand with a fineness modulus of 2.1 as sand, contains granite crushed stone of a fraction of 3-10 mm as crushed stone, and contains a complex chemical additive represented by an aqueous solution with a density of ρ=1.047 g/cm ³ , a pH value of pH=6.8, consisting of an aqueous solution of a polycarboxylate polymer of maleic anhydride with a density of ρ=1.027 g/cm ³ , a pH value of pH= 6.2; a high molecular weight compound based on the potassium salt of a higher fatty acid with a density ρ=1.056 g/cm ³ , pH value pH=9.2; silicon dioxide nanodispersions used in the form of silicon hydroxide sol with density ρ=1.012 g/cm ³ , pH=3.1; an aqueous solution of calcium nitrite with a density of ρ=1.038 g/cm ³ , pH value pH=5.7; an aqueous solution of calcium nitrate with a density of ρ=1,040 g/cm ³ , pH value pH=5.8 in the following ratio of additive components, wt. %: cauldron polycarboxylate polymer 37.74-39.00 specified high molecular weight compound 5.40-5.66 said nanodispersions 22.30-22.64 said aqueous solution of calcium nitrite 14.80-15.09 said aqueous solution of calcium nitrate 18.50-18.87, additionally contains a complex reactive stabilizer characterized by bulk density D=0.750 g/cm ³ , pH value pH=8.3, consisting of finely ground blast-furnace metallurgical slag with specific surface area S=470 m ² /kg; aluminous cement; methylcellulose with bulk density D=0.620 g/cm ³ , pH value = 7.3 and polycarboxylate polymer with copolymers of acrylic acid and methacrylic acid ethyl ester with bulk density D=0.620 g/cm ³ , pH value pH=6 ,3 with the following ratio of stabilizer components, wt. %: specified slag 81.06-82.0 aluminous cement 15.35-16.2 said cellulose 1.05-1.1 said polycarboxylate polymer 1.60-1.64, with the following ratio of components of the raw mix of high-strength concrete, wt. %: Portland cement 18.32-19.42 specified sand 30.16-30.56 specified rubble 39.89-40.39 specified stabilizer 3.30-3.39 specified complex chemical additive 0.14-0.18 water 7.09-7.16.